1. Field of the Invention
The present invention relates to mattresses with center ridge compensation.
2. Description of the Related Art
A mattress center ridge is characterized by two disadvantages of conventional mattress.
First, elevation of the surface along the center ridge is greater than the elevation of surrounding areas. Materials in a two-person mattress, such as a queen or king size mattress, become compressed in the areas of the surface where people sleep. By comparison, materials along the center of the mattress remain uncompacted, and over time present an elevated surface. The center ridge is also caused, or worsened, by the manner in which people enter and exit beds. As users sit on the edges of the mattress and roll into the mattress from the sides, materials within the mattress core are continuously urged toward the mattress's center. As a result, the center of the mattress may eventually have a greater density of material than the edges.
Second, firmness at the center of the mattress may be greater than firmness across the conventional sleeping areas. This results in part from the phenomena discussed above. It is also caused by fatigue in the mattress core over repeated used. Further, box springs for large mattresses may be provided in two sections. This design may presents a rigid upper surface to the mattress along a center line where two box springs meet.
There remains a need for a mattress design that prevents or mitigates the development of a center ridge.